324 KRAMM— SERPENTINES OF THE CENTRAL [June 6, 



hundred feet. It is possible to travel a short distance and measure 

 any angle. The rock is compact, specked with grains of biotite and 

 well consolidated. 



Outcrops of what is evidently the same sandstone are found a 

 few hundred yards northwest of IMorrell within the serpentine 

 mass. They resemble serpentine to such an extent that seen even 

 from a short distance they are taken for it. They have the rugged 

 appearance of serpentine outcrops and the same lighter tint green 

 which it often assumes upon weathering. A close inspection re- 

 veals the grain of the sandstone, decided bedding planes, and a 

 hardness which by far exceeds that of the serpentine. It also shows 

 the intense degree of metamorphism. At places a slight schistosity 

 has been developed. A thin section made of this rock contains the 

 usual acid ground mass of a sandstone, a few flakes of biotite and 

 considerable epidote. 



Crystalline schists and boulders of metamorphic rock are found 

 included in the serpentine on the crest of a ridge north of Knox- 

 ville. The serpentine is crushed to fine scaly masses resembling 

 a shale. 



About one half mile south of the Shamrock Mine a tributary to 

 Rocky Creek cuts the sandstone which butts against the serpentine 

 on the east of Rocky Creek. Narrow seams of interbedded shale 

 which carry AuccUa Piochii in abundance are exposed. Towards 

 the serpentine the sandstone is strongly metamorphosed. 



An actual contact of a shale with the serpentine is exposed by 

 the Johnson shaft of the Knoxville Mine. The shal'e however does 

 not seem to be much altered and it has not ben ascertained whether 

 or not it contains fossils. 



The mineralogical character of the serpentine combined with the 

 above evidence demonstrates that it is derived from an eruptive 

 rock which is intrusive into the Knoxville formation. 



There are two smaller areas of serpentine in the vicinity of the 

 Knoxville area. One is found about one mile south of Jericho 

 Creek. It approaches Hunting Creek in the west. It extends in a 

 northwestern direction approximately parallel to Putah Creek for 

 four or five miles. Its width varies from a few hundred feet to one 



